Saturday, 7 January 2012

OverviewIn this blog series I will be showing you how to create a ZigBee based home network for monitoring room temperature using Sena's ProBee Modules and OpenEneryMonitor's emoncms for recording and displaying the temperature data.Specifically, I'll be using the ZE20S modules with chip antenna for the sensor nodes and a ProBee-ZU10 usb dongle that will act as the network co-ordinator and feed temperature data into the monitoring computer.The following are assumptions on the readers knowledge/ability:

Basic understanding of ZigBee networks, for more info please see here and here.

Basic breadboard skills.

Access to a Linux based server for running the emoncms software.

ProBee ZigBee ModulesThe main thing I like about these ProBee modules is that they are cheaper than the corresponding XBee modules, and pretty much provide the same functionality (the ProBee modules actually have more digital and analog I/O pins that the XBee).The cheapest ZigBee compliant ProBee module (ZE20SSC-00 with chip antenna) costs about US$17. The cheapest ZigBee compliant XBee module (Series 2 XBee ZB with chip antenna) retails for around US$25! Interestingly both modules have an underlying Ember ZigBee chip with EmberZNet, Ember’s ZigBee compliant embedded mesh networking software.

Sena's ProBee Modules

System OverviewThe following diagram outlines the components of the system:

Overview of Network Components

ZigBee Temperature Sensor End Devices - Each end node will comprise of a ProBee ZE20S module, with temperature sensor, power supply circuit and batteries. As these nodes are battery powered, they will be configured to enter battery saving sleep mode and wake up periodically to report the temperature reading.

ZigBee Router - This will route the messages containing the temperature readings from the end devices to the ZigBee coordinator. The router is optional and only necessary if you don't have enough range between your end devices and Coordinator. It will consist of a ZE20S module and power supply. The router must remain powered on all of the time and as such will be mains powered.

ZigBee Coordinator - This will receive our temperature readings from the End Nodes in the network and display/store the measurements using the emoncms software. It will comprise of a ProBee USB dongle and, in my case, a Beagleboard. A PC or MAC could easily be used instead of the Beagleboard, as long as it runs emoncms.

Building The System

The following entries cover the steps that are required to complete our system: